1. Field of the Invention
The present invention relates to a PC card (this is a generic name referring to a memory card and an I/O card alike) usable in conjunction with electronic equipment including pin connectors that have different numbers of contact pins, such as, a personal computer, workstation, and multifunction telephone set.
2. Description of the Related Art
Referring to FIGS. 14, 15, 16, and 17, the structure of a known PC card will be described below. FIG. 14 is a perspective view illustrating a known PC card. FIG. 15 is a front view showing a connector surface of the known PC card. FIG. 16 is a block diagram showing the circuitry of the known PC card. FIG. 17 is a perspective view showing a known pin connector of a personal computer that is coupled with the known PC card.
In FIGS. 14 and 15, a known PC card 1 has 68 contact holes 5 formed in two rows (34 holes each) on a contact surface 2 of a socket (not shown) of the PC card 1, an incorrect insertion prevention ditch 6 formed on one side surface 3 of the housing of the PC card 1, and an incorrect insertion prevention ditch 7 formed on the other side surface 4 of the housing and shaped differently than the incorrect insertion prevention ditch 6.
In FIG. 16, the known PC card 1 includes circuitry comprising a control input port 10 connected to any of the contact holes 5, an address input port 11 connected to any of the contact holes 5, a mode control circuit 12 for controlling read and write modes, an address decoder 13 for selecting any of the chips constituting a semiconductor memory device that will be described later, an address input buffer 14 for inputting an address, a semiconductor memory device 15 consisting of a plurality of chips and having, for example, a storage capacity of 64 megabytes, a data input/output buffer 16 for inputting and outputting data, and a data input/output port 17 connected to any of the contact holes 5.
In FIG. 17, a known pin connector (standard pin connector) 20 has 68 contact pins lined up in two rows, an incorrect insertion prevention jut 22, and another incorrect insertion prevention jut (not shown).
The currently-prevailing standard specifications for the known PC card 1 are described in the PC Card Standard issued by the Personal Computer Memory Card International Association (PCMCIA) and the Japan Electronic Industry Development Association (JEIDA). This standard stipulates physical and electrical specifications for the PC card 1 using a 68-pin two-piece type connector. According to ongoing specifications for the PC card 1, the number of pins is limited to 68, therefore a maximum size for address space and a maximum transfer rate are 64 megabytes (A0 to A25) and 16 bits (D0 to D15) respectively. The configuration of the 68 pins (holes) is determined under the specifications: 26 pins are used as address pins (holes); 16 pins are used as data pins (holes), the remaining pins are used as control pins (holes) and power pins (holes).
The mode control circuit 12 controls the semiconductor memory device 15 and data input/output buffer 16 according to a read/write mode signal sent via the control input port 10, and places them in the read or write mode. The address input buffer 14 inputs an address (A0 to A25) via the address input port 11. The address decoder 13 outputs a chip select signal indicating any of the chips constituting the semiconductor memory device 15 to the semiconductor memory device 15 according to the high-order bits of the input address. The data input/output buffer 16 reads data (D0 to D15) from the semiconductor memory device 15 into a personal computer or writes data (D0 to D15) from the personal computer into the semiconductor memory device 15. Currently, semiconductor memory devices to be mounted in PC cards include larger storage capacities and personal computers accessing the PC cards are offering higher operating speeds. Accordingly, there is an increasing demand for a PC card having a large address space and/or permitting a higher transfer rate.
As far as the aforesaid known PC card is concerned, since the number of pins is limited, when a semiconductor memory device to be mounted has a larger capacity or a personal computer accessing the semiconductor memory device offers a higher operating speed, the PC card cannot be adapted.